Leachate and wastewater remediation system

ABSTRACT

A compact portable modular wastewater treatment system which integrates several processing technologies to provide a substantially purified water source. A wastewater stream is sent through an initial filtration step. The filtered wastewater is then subjected to electrocoagulation and then further filtered. The resulting stream containing substantially only organics is then treated in an advanced oxidation process which can include passing an electrical current through the water during the oxidation process. The partially treated water is then passed through ion-exchange columns to polish ammonium and other contaminants. The ion-exchange columns are cycled through regeneration cycles to provide continuous ion-exchange medium. The ammonium rich brine solution used in regeneration is subjected to an ammonium destruct process and then reused in regenerating ion-exchange columns. The water can then be sent through a final disinfection oxidation process to destroy or inactivate pathogens and/or remove any remaining colorants or odor to provide a water source suitable for almost any use.

PRIORITY CLAIM

[0001] This application claims priority to provisional application No.60/364,806, filed Mar. 15, 2002, the disclosure of which is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to wastewater treatment systems.

[0004] 2. Related Art

[0005] As the world's population grows and reserve supplies of cleanwater dwindle, the treatment of wastewater is becoming an increasinglyimportant concern worldwide. Beginning in 1972 with the Clean Water Act,the United States substantially increased government regulations onwastewater treatment. These regulations along with aging waterinfrastructure, global population shifts, and the time pressures ofexisting treatment facilities further highlight the growing pressures onwastewater treatment industry.

[0006] Conventional wastewater treatment facilities employ a single ormulti-stage process involving one or more of four main systems to removethe small amount of contamination contained in most wastewater. Thesesystems include settling systems, biological systems, chemical treatmentsystems, and filtration/polishing systems.

[0007] Settling systems often comprise a primary treatment phase andinvolve the removal of solids suspended in wastewater. Such settlingsystems typically include settling ponds, primary classifiers, and thelike. Larger solids are typically removed by screens, and smallersuspended solids by allowing them to settle to the bottom where theyform sludge.

[0008] Biological treatment systems typically form a secondary phase oftreatment, and are used primarily for the removal of organic materials.Typical biological treatment processes include facultative ponds,partially mixed lagoons, aerated lagoons, activated sludge, and thelike. All of these systems employ microorganisms which remove harmfulorganics from the water. These microorganisms are contained in largeponds or lagoons where wastewater must sit for several days in order toallow sufficient time for the microorganisms to interact with andneutralize the contaminants contained in the water. Biological systemsare highly effective and are used in approximately one third of alltreatment systems worldwide. However, biological systems have certainlimitations. For instance, if the microorganisms contained in thelagoons are shocked or killed by environmental changes or introductionof other agents, it can take weeks to produce a healthy colony oftreatment bacteria. Furthermore, biological processes produce anenormous amount of toxic sludge (comprised largely of deadmicroorganisms and their waste products), which must be subsequentlytreated before disposal. Additionally, due to the large costs and timeinvolved in constructing the facilities necessary for biologicalsystems, they must be planned out well in advance of the anticipatedneed and may not respond to short term increases in the need for watertreatment.

[0009] Various chemical treatment systems typically comprise a tertiaryphase of wastewater treatment. These processes are designed to removeharmful bacteria from the wastewater, including any remnants ofbiological treatment processes. Additionally these processes aredesigned to remove dissolved contaminants contained in the wastewaterstream. This phase can involve one or more of numerous processesincluding chlorination, ozonation, ion exchange or oxidation.

[0010] For most of the twentieth century, chlorination has been the mostcommon method for removal of microorganisms from wastewater. Whilehighly effective, chlorination has considerable drawbacks including thenecessity of containing, transporting, and manipulating large quantitiesof potentially lethal chlorine. Frequently, the expense of maintainingappropriate chlorination facilities and training qualified personnel arecost prohibitive for smaller wastewater treatment facilities.

[0011] Another common chemical treatment method is the introduction ofinorganic cationic coagulants such as aluminum salts and chlorides andsulfates of iron and calcium. Such treatments often create large amountsof residual sludge which must be disposed of. Further, chemicaltreatments are not well suited to influents of highly variablecompositions.

[0012] The final phase of conventional wastewater treatment typicallycomprises polishing. During this phase the water is often filtered andtreated depending on the particular waste-stream so that any unwantedcoloration or odor is removed. Following this phase, the water istypically ready for discharge into the environment, consumption, orother use.

SUMMARY OF THE INVENTION

[0013] In view of the foregoing drawbacks to conventional wastewatertreatment systems, a wastewater treatment system constructed andconfigured to be a turn key system, scalable to the needs of manysituations, and capable of treating wastewater having low to hightoxicity without the storage of hazardous chemicals continues to besought.

[0014] It has been recognized that it would be advantageous to develop awastewater treatment system which solves the aforementioned problems.The present invention provides an effective system for addressing manyof the difficulties encountered in wastewater treatment.

[0015] The present invention encompasses a compact, portable, scalable,wastewater treatment system allowing for effective wastewater treatmentmeeting the immediate needs of any community, environmental, orindustrial plan without extensive planning prior to implementation. Thishas been achieved through the creation of a wastewater treatment systemthat can comprise up to six primary phases which include: initialscreening, an electro-physical separation, an advanced oxidationprocess, a fine filtration, ion exchange and a final disinfection step.The particular choice of process phases will depend on the properties ofthe waste-stream to be treated.

[0016] More specifically, in one potential embodiment of the presentinvention, these phases can include the step of removing large solidsfrom a wastewater influent stream by passing the influent wastewaterstream through a series of screens to create a primary, screenedwastewater stream. The primary wastewater stream can then be directed toan electrocoagulation unit. A variety of electrocoagulation unitconfigurations can be used in the present invention in order to removeand flocculate a wide variety of contaminants. Dissolved, colloidal, andemulsified contaminants can be removed from the primary, screenedwastewater stream by applying an electrical current to theelectrocoagulation unit to induce precipitation and flocculationresulting in a secondary wastewater stream. An optional flocculantmaturation unit can be included to allow for further formation of largerparticulates. Fine particulate matter and flocculants can then beremoved by passing the secondary wastewater stream through one or morefine filters to create a wastewater stream contaminated substantiallyonly by unfiltered organics. The organically contaminated wastewaterstream can then be subjected to an advanced oxidation process to createa tertiary wastewater stream. The tertiary wastewater stream can then becontacted with zeolites, allowing an effective amount of reaction timewith the zeolites to create a polished water stream. The polished waterstream can then be exposed to ozone to create a final decontaminated ordisinfected water stream. Periodically, under some conditions, thezeolites can be refreshed with a brine solution using a process whichallows for continuous processing of wastewater streams.

[0017] Additional features and advantages of the invention will beapparent from the detailed description which follows, taken inconjunction with the accompanying drawings, which together illustrate,by way of example, features of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a flow diagram of the basic process of the presentinvention.

[0019]FIG. 2 is a schematic view of an embodiment of theelectrocoagulation module.

[0020]FIG. 3 is a schematic view of the solids dewatering unit inaccordance with the present invention.

[0021]FIG. 4 is a schematic view of the ion-exchange columns inaccordance with the present invention.

[0022]FIG. 5 is a schematic view of an ammonium destruct unit inaccordance with the present invention.

[0023]FIG. 6 is a graph showing ammonium destruct rate in the ammoniumdestruct process.

[0024]FIG. 7 is a perspective view of one embodiment of a degassing unitin accordance with the present invention.

[0025]FIG. 8 is a cut away view of a unique static mixer pipe for use inthe present invention.

DETAILED DESCRIPTION

[0026] Reference will now be made to the exemplary embodimentsillustrated in the drawings, and specific language will be used hereinto describe the same. It will nevertheless be understood that nolimitation of the scope of the invention is thereby intended.Alterations and further modifications of the inventive featuresillustrated herein, and additional applications of the principles of theinventions as illustrated herein, which would occur to one skilled inthe relevant art and having possession of this disclosure, are to beconsidered within the scope of the invention.

[0027] The singular forms “a,” “an,” and “the” include the pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to “a heat source” includes reference to one or moresuch heat sources.

[0028] As used herein, “effective amount” refers to the minimal amountof a substance, agent, action, or time period to achieve a desiredeffect. For example, an effective amount of “cooling” is the minimumamount of heat loss required in order for a given substance to reach adesired stable temperature.

[0029] As used herein, “wastewater stream” or “water stream” refer to abody of water contained within the present invention, whether said bodyof water is in motion or not. Furthermore, “wastewater” and“contaminated water” are used interchangeably and include any body ofwater having undesirable components for a particular purpose. Thus, suchwastewaters can include heavily contaminated mine and landfill leachatesand also potable water needing minor clarification.

[0030] The terms “formulation” and “composition” may be usedinterchangeably herein.

[0031] The terms “fluid” and “solution” may be used interchangeablyherein.

[0032] Concentrations, amounts and other numerical data may be expressedor presented herein in range format. It is to be understood that such arange is used merely for convenience and brevity and thus should beinterpreted flexibly to include not only the numerical values explicitlyrecited as the limits of the range, but also to include all theindividual numerical values or sub-ranges encompassed within that rangeas if each numerical value and sub-range is explicitly recited.

[0033]FIG. 1 illustrates a wastewater treatment process according to thepresent invention. At step 101, the wastewater to be treated isidentified. Depending on the composition of the particular wastewaterstream the following process can be modified to treat the water based onparticular needs, i.e. potable versus non-potable uses. Further, somewastewater streams may not require some steps such as the prescreening,if such stream is devoid of substantial particulates. Any number ofwastewater compositions can be treated in this process and the processof the present invention is highly effective at treating a wide varietyof contaminated wastewater. The wastewater subjected to treatment can beindustrial effluents, sewage, landfill leachate, acid mine effluents,mining or other commercial effluents, potable water sourceclarification, ground-water clarification, storm water treatment,mineral processing effluents, or any other contaminated body of water.The wastewater can contain a variety of contaminants such as, but notlimited to, emulsified oils, hydrocarbons, dissolved particles,suspensions, undesirable minerals, bacteria, viruses, perchlorates,colorants, heavy metals, ammonium, toxic organics, chlorinated organics,pesticides, cyanide, arsenic, and a majority of other contaminants. Thesystems and methods of the present invention are capable of treating avariety of wastewater including those having extremely high levels ofcontaminants or merely as an additional disinfection and final polishingtreatment.

[0034] Initial Screening

[0035] The contaminated water influent can be optionally subjected to aninitial screening step 102 which removes large solids and particulatesfrom the incoming water stream. This step may be unnecessary in thetreatment of some influents, although clearly some care should be takento prevent particulates from unnecessarily passing down stream. Thisstep involves typical screening and filtration technologies and thechoice of particular methods is within the skill of those in the art.Various screens, filters, classifiers, or centrifuges could be used. Theprimary function of this step is to remove larger solids, i.e. largedebris, and particulates, i.e. those above about 100 μm, from the waterstream. Further, the initial screening can include several steps such asa 0.5 inch bar screen followed by a gravimetric classifier or cyclone.Additionally, in order to provide continuous filtration of influentsstreams a variety of on-line/off-line cycles can be used. For example,in one embodiment of the present invention a plurality of filters areincorporated into a single unit. Influent is directed through several ofthese filters while one or more filters are cleared either by reversedfluid flow or other similar processes. The cycles of filtration andclearing can be controlled by computer driven valves or manually.

[0036] Ozone Pretreatment

[0037] Following the initial screening 102 step, an optional ozonepretreatment step 102B can be performed. Depending on the level ofcontaminants of the influent waste-stream a pretreatment of betweenabout 1 and about 2 ppm of ozone can be added. The ozone can be added ineither a tank or along a mixing pipe as described in more detail below.

[0038] Electro-physical

[0039] Following this screening and filtration process or optional ozonepretreatment, step 103 includes an electro-physical process whichremoves dissolved particles, emulsified oils, colloidal material andminerals suspended in the water. This electro-physical process resultsin the removal of a vast majority of the contaminants. This process ishighly effective at killing bacteria and viruses, and is effective inremoving the majority of contaminants such as, but not limited to,arsenic, aluminum, barium, biochemical oxygen demand (BOD), cadmium,calcium, chromium, coliform, colorants, copper, cyanide, oils, iron,lead, magnesium, manganese, mercury, molybdenum, nickel, pesticides,phosphates, silicon, sulphates, total suspended solids (TSS), silver,vanadium, volatile organic solids, and zinc.

[0040] Arsenic removal is particularly significant because newregulations on arsenic removal require municipalities to remove morearsenic from treated drinking water. Requirements have become morestringent from previously allowing 50 parts per billion to only 10 partsper billion of arsenic in treated drinking water by 2006. The improvedelectro-physical and ion exchange processes of the present inventionmeet these requirements.

[0041] The electro-physical process involves electrocoagulation, whichis the process of destabilizing suspended, emulsified or dissolvedcontaminants in an aqueous medium by introducing an electrical currentinto the contaminated wastewater. The electrical current provides theelectromotive force to drive the chemical reactions to a newequilibrium. When reactions are driven or forced, the elements orcompounds will approach a new stable state. Generally, this state ofstability produces a solid that is either less colloidal and lessemulsified or soluble than the compound at the original equilibriumvalues. As this occurs, the contaminants form hydrophobic entities thatprecipitate and can easily be removed by a number of secondaryseparation techniques. Thus, this process is often referred to aselectrocoagulation. In addition to changing equilibrium, application ofan electrical current also causes hydrolysis of a portion of thewastewater. This hydrolysis releases hydrogen and oxygen gas into thewastewater to form hydroxyl ions. The hydroxyl ions react with metalsand other contaminants which then precipitates out and the oxygen actsas a moderate oxidizer of other contaminants.

[0042] The actual application of electrical current to the wastewaterstream can be provided in a number of ways such as parallel conductingplates or an annular configuration. The particular electrocoagulationunit can be configured in a variety of ways and yet achieve goodresults. FIG. 2 depicts one embodiment of the electrocoagulation unit201 in accordance with the present invention which is effective. Aplurality of tubes 202 are provided each having an electrode 203 placedin the center thereof which extends a majority of the length of thetube. The wastewater is delivered to one end of the tube via inlet 204and travels the length of the tube and exits the tube at outlets 207.Non-conducting spacers 205, such as nylon or other polymer, can be usedto prevent contact between the electrode and the inner surface of thetube. The size of the outlets 207 and the spacers 205 should be chosento prevent agglomeration or clogging. Typically a spacing of about ⅛′has proven adequate although other spacing distances can also besuccessfully utilized.

[0043] A voltage is applied to the electrode to produce a voltage acrossthe space between the electrode and the inner surface of the tube. Thevoltage across this space should be sufficient to causeelectrocoagulation of a substantial portion of the contaminants. A DCvoltage of about 5 to about 6 volts and about 700 A across this space ata flow rate of about 0.1 gpm per tube has provided good results,although between about 2V and about 15V would suffice for mosttreatments using an electrocoagulation unit as shown in FIG. 2 andhaving 72 electrodes. Of course, different voltages would be required byvarious configurations which can be determined by those skilled in theart. In order to further improve the electrocoagulation process resultsa pulsed current and/or periodic reversal of polarity can be applied tothe electrodes. These variations of current enhance the destruction ofbacterial and other cell membranes, increase flocculation, and reducescale buildup on the anodes.

[0044] In the embodiment shown in FIG. 2, these tubes are arranged in anarray of tubes placed parallel to one another side-by-side in agenerally circular configuration. Notice that only two such tubes areillustrated for clarity, however a variety of arrangements would satisfythe requirements of the present invention. Thus, for exampleconsecutively annular tubes each acting alternately as an anode or acathode is another possible configuration. Another possibleconfiguration includes spiralized cathode and anode plates which areinterwoven without contact such that fluid flows between the coiledplates from the center toward to outer diameter along a spiral path asdisclosed in patent application __/____, filed Mar. 10, 2003, entitledElectrocoagulation System and Method of Use, which is herebyincorporated by reference in its entirety. The tubes and electrodes areconstructed of various metals that are selected to optimize the removalprocess. The most common materials are iron, aluminum and their alloysalthough other materials which provide ions could be used such as steel,platinum, carbon, magnesium, conductive ceramics and plastics, titaniumand other ferrous alloys. In accordance with Faraday's Law, metal ionswill split off or be sacrificed into the liquid medium; these metal ionstend to form metal oxides that electro-mechanically attract to thecontaminants that have been destabilized. These electrodes, ifsacrificial, will eventually require replacement or cleaning.

[0045] Referring again to FIG. 2, in this configuration a filter 206 isplaced in the center of the array of tubes and is designed to remove thecoagulated contaminants from the liquid. The filter can be any filterwhich is capable of removing particulates which are about 1 to 5 μm andlarger. The filter shown in FIG. 2 is a cylindrical filter where theliquid from the tube outlets 207 is drawn through the filter to outlet208 at the top of the electrocoagulation unit. Notice that the inlet endof the tubes are lower than the outlet ends. Although not required, thisconfiguration improves the contact of particulates and fluid past thefilter surface. Various factors influence the rate of electrocoagulationsuch as: residence time of the wastewater, applied current and voltage,turbulent flow characteristics, temperature, electrode surface area, andconcentration of contaminants in the wastewater.

[0046] In a more detailed aspect of the present invention, in order toprevent excessive build-up of filtered particulates on the outer surfaceof the filter 206 various methods can be used to continuously orperiodically remove the particulates. These methods include but are notlimited to, air pulses, shaking, physical cleaning, or other knownmethods. In one embodiment of the present invention sixty nozzles placedin the center of the filter provide the necessary removal. For example,40 psi air can be provided at a pulse rate of 1 pulse per second toobtain adequate results. The removal process can be performedperiodically based on the performance of the filter. During this removalprocess, the unit is typically shutdown by closing valves 208 and 204and opening valve 209. Pressure is then applied to the air nozzles todislodge particulates which are then forced out of the unit via line209. This removal process is preferably computer controlled at regularintervals but can also be manually performed.

[0047] The particular configuration of the clectrocoagulation unitdescribed also provides for increased turbulence in the wastewater flowtherethrough. It is known that turbulent conditions improve the life ofthe electrodes by minimizing electrode deposition, erosion, and foulingand improves conductivity through the wastewater medium.

[0048] The coagulated solids are then removed as a slurry from the unitvia outlet 209 and the substantially purified water is removed viaoutlet 208 once 209 is closed. Electrocoagulation produces significantlyless residual solids than conventional chemical treatments. Typically,about 0.2 lb of metal per 1000 gallons of treated water is sacrificedfrom the anode to flocculate with contaminants but varies widelydepending on the incoming stream.

[0049] Although, the above electrocoagulation unit has been described indetail, other configurations and modifications which would occur to oneskilled in the art are deemed within the scope of the present invention.

[0050] Tests have shown that the above contaminants are removed at overabout 90%, and predominantly over 95% for each contaminant listed exceptammonium, mercury, and molybdenum. Table 1 shows the results of atypical treatment according to this step of the present invention. TABLE1 Electrocoagulation Results Contaminant Percent Removed Aluminum 99+Ammonium 60 Arsenic 94 Bacteria 98 Barium 98 BOD 97 Cadmium 98 Calcium96 Chromium 99+ Total Coliform 99+ Color Removal 99+ Copper 99+ Cyanide90 Oils 94 Iron 97 Lead 95 Magnesium 98 Manganese 96 Mercury 65Molybdenum 80 Nickel 99 Pesticides 98 Phosphates 97 Silicon 98 TSS 98Silver 99+ Vanadium 95 Volatile Solids 97 Zinc 99+

[0051] Liquid/Solid Separation

[0052] As shown in FIG. 1, after electro-physical treatment step 103 theresulting solids are delivered to a solids treatment step 104. Duringthis step the solids slurry recovered from step 103 is separated and thewater is sent back to the process for further treatment (either step 103or the following step 105, discussed below). Although a number offiltering devices could be used and are considered within the scope ofthe present invention, FIG. 3 shows one particularly effectiveembodiment. In this embodiment, the solids slurry is delivered via inlet301 to a generally drum or v-shaped shaped container 302. A filter cloth303 is provided at one end of the unit which follows the contour of thecontainer bottom and is drawn up the other side and collected at roll304. In one aspect, a direct pressure member (not shown) is used toguide the cloth and force it against filter 305. As the cloth isadvanced the direct pressure member can be displaced slightly to allowfree movement of the filter cloth. The water is drawn through filter 305by pulling a low pressure on the underside of the filter to create apressure differential. As the filter cloth becomes saturated withparticulates it is replaced. This is most often accomplished by movingthe filter cloth across the filter at a constant rate while maintainingthe pressure differential. For example, a 45 lb weight geotextile filtercloth having 150 to 210 μm pores can be drawn at a rate of between about150 and 900 gall/yd². This rate may vary widely depending on theparticular wastewater stream and is adjusted based on experience. Thefiltered water is then removed from the unit via line 306. Most oftenthis water is of sufficient clarity to send to the advanced oxidationprocess step 105 discussed below. These units have a space savingconfiguration that ensures the maximum filtration power is generatedwithin a small footprint.

[0053] Advanced Oxidation Process

[0054] Following the electrocoagulation step 103 the water is thentreated in an advanced oxidation process (AOP) at step 105. An oxidizer,such as ozone, fluorine, hydrogen peroxide, potassium permanganate,hypobromous acid, hypochlorous acid, chlorine, or mixtures thereof, isforced through the water in high concentrations. As an optionalenhancement, an electrical variable or pulsed current from anon-sacrificial anode is driven through the water to be treated. Thecurrent causes the formation of hydroxide ions which in combination withthe oxidizer interacts with the water, reducing remaining impuritiessuch as hydrogen sulfide, iron, algae, fungus, mold, yeast, bacteria,virus and ammonium. Although other oxidizers could be used ozoneprovides excellent results and is readily produced on-site. In analternative embodiment other agents can be added during the oxidationprocess such as air and/or ultraviolet light. It is important to notethat the advanced oxidation process utilizes significantly higherconcentrations of ozone than is typically used for disinfectionprocesses. Specifically, a remediatively effective amount of oxidizingagent is added to the water. In the present invention, ozone is used atan earlier stage and in higher concentrations which are sufficient tofully saturate the solution and are generally from about 2 to about 5times higher than is used in typical ozone disinfection process ozoneconcentrations. The exact concentrations necessary for a remediativelyeffective amount will vary depending on the waste stream. As a generalguideline, however, ozone disinfection processes use from 2 to as highas 30 ppm, but are typically about 5 ppm. The process of the presentinvention utilizes ozone concentrations which are about 2 to about 5times greater than would be used in standard polishing ozonedisinfection processes. Thus, a remediatively effective amount can be aslow as about 4 ppm to as high as about 200 ppm. In addition, thesolubility of ozone in solution depends on a variety of factors such astemperature, pressure, and other components in solution. Of courseconcentrations outside this range can be used depending on the nature ofthe influent wastewater. During the advanced oxidation process pressuresof between about 20 psi and about 60 psi can be used. This advancedoxidation process step can remove BOD, chemical oxygen demand (COD),residual precipitatable components, and other contaminants. Removing asubstantial portion of these types of contaminants at this phase in theprocess helps to reduce the load and the rate of depletion of theion-exchange columns described below.

[0055] In one embodiment of the present invention, static pipe mixers(described below in conjunction with FIG. 8) are utilized which allowfor thorough mixing of the ozone and waste-stream and improved reactionand residence times.

[0056] Ozone is a particularly desirable oxidizer, not only for thestrong oxidizing properties, but also for the ease of production andavailability. At step 106 ozone is produced from air using any number ofknown technologies. For example, in one process, air is collected andthe oxygen content is increased using commercially available oxygenconcentrators. The oxygen is then subjected to electric exhalation atbetween about 10 and 20 kV to produce ozone. Ozone produced in thismanner merely requires air, electricity and a cooling medium such aswater or air. The ozone produced from this step can be used throughoutthe process. Typical commercial ozone units produce ozone at a lowpressure. As a result, the steps of the present invention which utilizeozone are typically below a pressure of about 10 psi.

[0057] Microfiltration

[0058] After the AOP step an optional microfiltration step 107 can beperformed to further clarify the partially treated wastewater. This stepremoves particles which are about 1 μm or larger using standard filtersknown to those skilled in the art.

[0059] Ion Exchange

[0060] Following the AOP step 105 (or optional microfiltration step107), the partially treated wastewater is further treated inion-exchange step 108 to remove residual dissolved ions such asammonium. Natural or synthetic zeolites can be used to conduct ionexchange and remove the ammonium from the water as it passes through thezeolite chambers. However, it will be appreciated that materials such asclays, clay-like minerals, expandable clays, ferrous sulfate impregnatedceramics, chabazite, carbon, or any other material which act as an ionexchange medium with ammonium can also be used in connection with thepresent invention. These can include natural or synthetic materials. Forinstance, both naturally occurring zeolites and artificially synthesisedzeolites have been investigated for use as the mineral substrate of thepresent invention. Zeolites (hydrated aluminosilicates) are a moderateto high cation exchange capacity material and although they arealuminosilicate minerals like clays, they have a various threedimensional framework structure with internal cavities characterized byhigh surface areas. The zeolite structure acts as a molecular sieve toremove ammonium and other cations from the contacted solution. Types ofzeolites include: clinoptilolite, chabazite, phillipsite and mixturesthereof. Because natural sources of zeolites often contain mixtures ofzeolites instead of one single zeolite and some zeolites share severalcommon characteristics. Therefore, the term “zeolite”, as used herein,will refer to one zeolite and also to a mixture of zeolites with thedesired properties.

[0061] Selected zeolites enable ammonium ion and various metal ions tobe separated from wastewaters, as disclosed by Weber in U.S. Pat. No.4,522,727, for example. Preferential zeolitic separation of ammonium(plus heavy metals) from alkali metal ions in solution is taught byHagiwara and Uchida, using a modified mordenite in “Ion-ExchangeReactions of Processed Zeolite and Its Applications to the Removal ofAmmonia-Nitrogen in Wastes” (at pp. 463-470) in Natural Zeolites, etc.,International Conference 1976, published by Pergamon in 1978. Breck inU.S. Pat. No. 3,723,308 characterizes an artificial zeolite (F) asuseful to remove ammonium without removing so much alkali or alkalineearth metals as can occur with natural zeolites.

[0062] In step 108 the wastewater is processed through a system ofion-exchange columns. Wastewater from either steps 105 and/or 107 entersthe ion-exchange process via line 401 shown in FIG. 4. In the embodimentshown in FIG. 4, a system of three sets of columns 402, 403 and 404 areshown. Although not required, these columns are typically packed bedcolumns configured such that the inlet is at the bottom of the columnand the outlet is at the top of the column to prevent channeling. Thewater is then removed via line 408 and sent to the next step of theprocess 110 described below. Optional screens and/or zeolites having avariety of mesh sizes can be placed within the column. The screens wouldpreferably be a finer mesh toward the center of the columns and coarsermesh toward the ends. In addition, it is often beneficial to includelarger zeolite particles toward the ends of the columns and finerzeolite particles toward the center in order to reduce the possibilityof smaller zeolite particles from escaping the columns.

[0063] The wastewater to be treated is sent to one or more of the setsof columns. Periodically, fluid can be sent through the columns in areverse path in order to dislodge particulates which may haveaccumulated at the screens or throughout the column. Additionally, asthe zeolite, or other ion-exchange medium, is used the efficiency beginsto decrease as the available pores within the zeolite structure areoccupied. Monitoring of the column performance will indicate when eachcolumn or set of columns has been saturated. In order to providecontinuous operation, the saturated columns are periodically takenoff-line to remove the ammonium in a regeneration step and a recentlyregenerated column is brought on-line such that there is no interruptionin the overall production of treated water. Thus, for example columns402 ands 403 would be online while columns 404 were being regenerated,wherein valves 405, 406 and 407 would control which sets of columns wereonline at any given time. The online sets of columns can be operatedeither in series or in parallel. When the online sets of columns areoperated in series it is preferable, although not required, that themost recently regenerated column is second so that the water stream ispolished with fresher column.

[0064] Regeneration of the columns is accomplished by flushing thecolumn with a brine solution, wherein sodium or like molecules displacethe ammonium which is then removed from the zeolite column. Theconcentration of sodium or other cation must be sufficient to drivesubstantially all of the ammonium from the ion-exchange material.Typically, rinsing with the brine solution for no less than about 4 to10 bed, i.e. column, volumes is sufficient to regenerate substantiallyall of the zeolite of the column. The brine solution is typically about2% to about 5% minimum concentration. This process allows eachion-exchange column to cycle through a series of online ammonium removaland offline ammonium destruction, zeolite replenishment cycles.

[0065] Once the ammonium is removed from the columns it is treated instep 109 in an ammonium destruct process. The following is a discussionof this process. An effective amount of bromine is added (typically inthe form of sodium bromide) to the brine solution removed from thecolumns to aid in the ammonium destruct process. The following reactionsequences illustrate the known effect of bromine as a catalyst on such aprocess using ozone.

[0066] Reaction with Bromine

[0067] Br⁻+O₃ BrO⁻+O₂

[0068] Br⁻+O₃ (O₂+BrOO^(−) Br) ⁻+20₂

[0069] BrO⁻+2O₃ BrO₃ ⁻+2O₂BrO⁻+H₃O HBrO+H₂O

[0070] HBrO+NH₃ NH₂Br⁺+H₂O

[0071] NH₂Br+3O₃ 2H₂O NO₃ ⁻+Br⁻+3O₂

[0072] Reaction without Bromine

[0073] NH₃+4O₃ NO₃ ⁻+4O₂+H₃O⁺

[0074] (Occurs very slowly below pH of 9.3) The resulting solution is abrine solution which can then be reused to again regenerate theion-exchange columns. In an alternative embodiment a secondelectrocoagulation unit can be operated on the ammonium containingeffluent prior to the above chemical treatment.

[0075] Referring now to FIG. 5, the ammonium-rich brine solution removedfrom the zeolite columns 511 which are in the process of regeneration isdirected via line 501 to the ammonium destruct step process 109. Theammonium-rich brine solution recovered from the columns varies inammonium concentration over time. Specifically, the initial volumes ofbrine solution contain a majority of the ammonium. For example, thefirst few bed volume may contain as much as about 85% of the totalremoved ammonium. FIG. 6 shows a typical ammonium concentration curveshowing the ammonium destruct rate in a solution having ammoniumintroduced at the point where ammonium concentrations reach a specifiedminimum. It should be noted that the rates shown in FIG. 6 are onlyrepresentative as rates as much as 20% greater have been achieved undersome conditions. Further, it has been found that segregating the initialbrine solution having a high ammonium concentration from later lowerconcentration solutions improves the ammonium removal rate from thezeolite columns and ammonium destruct process. Thus, as shown in FIG. 5,incoming ammonium-rich brine is fed along line 501 initially throughvalve 502 and into tank 503. Once the ammonium concentration is belowthe desired range, valve 502 is closed and valve 504 is opened to permitflow via line 505. Ozone is then injected via line 506 and theammonium-containing brine is sent to reactor 507. In one detailedaspect, the ozone stream in line 506 and/or the brine can be cooled inorder to increase the ozone concentration of the solution.

[0076] Although other configurations can be effectively used, onecurrent embodiment utilizes a reactor 507 which is a pipe reactorcontaining a plurality of spaced apart in-line static mixer pipes 507 a,described in more detail below in conjunction with FIG. 8. As thesolution flows through reactor 507 a substantial portion of the ammoniumis destroyed at the rate shown in FIG. 6. The solution can then be sentto a holding tank 508, shown in FIG. 5, where the remaining ammonium isconverted leaving a solution which is largely void of ammonium andsuitable for reuse as the brine solution. The solution can then be sentto a second tank 509 for reuse in regenerating zeolite columns 511. Overtime the solution becomes saturated with ozone. Periodically, or on agradual continuous basis, a portion of the ozone is released fromsolution by an optional degas valve, preferably placed between thereactor 507 and the holding tank 508. Alternatively, a set of reactor507 and holding tank 508 systems can be used alternately. Thus, as onesystem is off-line the ozone is allowed to separate into the open spacein the tank thus reducing the ozone concentration of the solution.

[0077] Although a variety of degas valves can be used, FIG. 7illustrates one currently developed configuration. Ozone saturatedsolution is received via line 701 into a unit having a typicalhydrocyclone feed manifold 702. The unit has an outer cylindricalhousing 703 and an inner cylindrical pipe 704. The ozone saturatedsolution flows in a spiral vortex through the annular space between 703and 704. The inner pipe 704 can include a plurality of slits which allowthe ozone to escape toward a typical degas valve 706. The ozone can thenbe recirculated for use in other parts of the system or sent to theozone destruct process. In order to improve mixing and ozone separationa flow directioning member 705 can be added in the annular space. FIG. 7shows a tube which is wrapped around the inner pipe to cause circularflow of the solution as it moves toward the bottom outlet 707. The flowdirectioning member 705 can be any obstruction which directs the flowsuch as a tube, flange, baffling, or other similar members. It should benoted that using a typical degas valve alone generally allows for excessozone to be released which increases the required ozone. This isundesirable as the ozone concentration should be merely reduced slightlyrather than completely vented.

[0078] Referring again to FIG. 5, the concentrated ammonium-rich brineheld in tank 503 can be slowly introduced into the reactor 507 via line510 either before or after the ozone injection point. By monitoring theammonium concentration at various.points the flow rate of ozone,concentrated ammonium-rich brine, and other flow rates can be adjustedas necessary. Various additional configurations can also be utilized toimprove the efficiency and rate of the ammonium destruct process. In oneaspect of the present invention, a second reactor 507 and holding tank508 combination can be operatively connected to the first reactor andholding tank set such that the ozone and ammonium-containing water canbe cycled between the two systems until the desired ammonium levels arereached. In order to maximize the recovery of ammonium from the zeolitecolumns during the regeneration cycles, brine solutions havinginsignificant concentrations of ammonium are preferably used toregenerate the columns.

[0079] In addition, as the brine solution is cycled through the zeoliteregeneration and ammonium destruct processes it is heated by warm ozoneand pressure changes. The increase in temperature reduces the solubilityof ozone in the solution and thus the ammonium destruct rates. Thus, itis beneficial to cool the brine solution using any number of knowncooling processes such as heat exchangers or the like. In oneembodiment, the ozone saturated brine solution can be sent through abaffled tank which acts as a compact heat exchanger.

[0080] In one detailed aspect of the present invention,electrocoagulation can be optionally performed in conjunction with theammonium destruct process. Such treatment can be performed either justbefore injection of ozone or at a later stage. Such additionalelectrocoagulation treatment has proven to further enhance contaminantremoval and the ammonium destruct rates.

[0081] The ammonium destruct process can be efficiently enhanced usingstatic mixer pipes such as that shown in FIG. 8. Two concentric pipes801 and 802 having an annular space between them is provided. A portionof fluid is passed through the center pipe 802 to decrease the pressurechange upon entry of the mixer and to improve exit mixing by providingat least two flow paths of substantial volume. A flexible tube 803 iswrapped around the outside of the inner tube 802 to cause spiral motionof the fluid which is directed through this annular space. Other flowdirecting member can be utilized besides a flexible tube such as solidflanges, baffles, or the like. Such flow directing members can beattached to either the inner or outer pipes or both as long as asubstantial portion of the flow therethrough is directed in a spiralmotion along the length of the pipe mixer. In addition, this flexibletube or other flow directing member can contain a plurality ofmicro-slits which allow for introduction of a liquid and/or gas, such asozone, air, polymers, etc, to the fluid. One advantage to using aflexible polymeric tube is that upon application of pressure the slitswill open allowing the gas and/or liquid to enter the annular space andupon reduction of pressure the slits will return to a closed positionthus controlling the amount of gas and/or liquid and preventing backflowof the same. As the fluid exits this mixer the components are furthermixed without the use of additional energy. This configuration allowsfor mixing without the requirement of extra pump or energy consumingmixers. Such mixers can also be placed in other parts of the process toincrease mixing and improve contact between compositions. In analternative embodiment of the mixer pipe, the inner tube 802 can beslightly perforated to allow some movement of material between the innerpipe and the outer pipe. Specifically, it may be desirable to reduce gascontent of the fluid in the inner pipe. The vortex motion of the outerfluid acts to cause a pressure differential between the inner and outerpipes which will aid in this process. Additionally, these mixer pipesare particularly suited for use in other parts of this process such asadvanced oxidation process, ozone pretreatment, ozone disinfection, orother steps.

[0082] Ozone Destruction

[0083] In order to comply with federal regulations, excess ozone must bedestroyed and cannot be released into the atmosphere. Thus, excess ozonefrom any of the process steps discussed herein can be destroyed usingknown technologies such as thermal and catalytic systems. In oneembodiment, the present invention utilizes a heating element inconjunction with a manganese dioxide catalyst. Care should be taken toavoid allowing moisture into such a catalyst system as water willdeactivate the catalyst.

[0084] Final Disinfection

[0085] Following the removal of ammonium, or other unwanted ions, by thezeolites described above, the water is sent to a final disinfection step110. Ozone (O₃), a powerful oxidizer, is used to remove or destroy anyremaining pathogens, contaminants, odors, and color from the treatedwater. Although ozone has been used for centuries to treat water, thepresent invention employs a process to ensure maximum oxidationtreatment power. In this final disinfection step, the water is sentthrough a pipe reactor containing static mixers under low pressure. Theresulting mixture is supersaturated at these conditions and provides foran unexpected improvement in the oxidation process. In an alternativeembodiment of this step of the present invention, air and ultravioletlight can be added to the water during the oxidation process.

[0086] The resulting treated water 111 is suitable for use in a varietyof applications and is substantially free of high levels ofcontaminants. The treated water is typically ready for use as potablewater or used as irrigation or make-up water in other processes. Forexample, mine wastewater from an EPA superfund site having highconcentrations of metals was treated using the process of the presentinvention. Table 2 outlines the measured values (mg/l) of several metalcontaminants from this mine wastewater as illustrative of some of themany contaminants which can be removed. TABLE 2 Arsenic Cadmium LeadZinc Iron Before 7.22 0.284 0.011 34.2 120 Treatment After 0.002-0.015<0.001 0.002 0.03-0.18 0.03-0.06 Treatment

[0087] Modular Nature of System

[0088] In a detailed aspect of the present invention, the abovedescribed processes and units are highly modular such that variouschanges can be made to accommodate a variety of waste-streams.Specifically, it is important to first assess the waste-stream to betreated for contaminant levels and types, i.e. high concentrations ofmetals, organics, etc. For example, a very different configuration maybe necessary to treat a mine leachate stream having high levels ofmetals than would be required to treat a sewage waste-stream having highlevels of organic and solid wastes. Once the waste-stream ischaracterized the appropriate configuration can be designed to mostefficiently remove the identified contaminants. In one embodiment of thepresent invention, the process includes an initial prescreeningfiltration step followed by treatment using electrocoagulation. Asdescribed above the solids are sent to a solids filter and the remainingwaste-stream is subjected to the advanced oxidation process (AOP). Inanother more detailed aspect, following the AOP step the water can befurther filtered or polished using ozone disinfection. Waste-streamssuch as, but not limited to, those containing high levels of organics,sewage, landfill leachate, and the like are particularly suited to theuse of the zeolite/ion-exchange columns. Likewise, a contaminated watersource such as a low toxicity groundwater or other nearly potable waterwhich merely need a final polishing process may only require the use ofa simple filtration step and the ion-exchange and regeneration steps.

[0089] In one preferred embodiment of the present invention, the entireprocess as described above can be mounted on a trailer-truck bed. Such aportable configuration allows for quick startup and requires minimalspace. Furthermore, remote waste-streams can be treated over short orlong periods of time without the associated building costs of morepermanent facilities. The volume of waste-stream influent which can betreated using such a trailer-truck configuration will vary considerablydepending on the specific waste-stream properties, however highlycontaminated streams have been treated at a rates of between 2 and 70gpm. It should also be noted that several of the processes and unitsdescribed above can be optimized for use in this compact and portableenvironment. For example, the spiral configuration of the pipe reactorshown in FIG. 5 not only reduces space but increases mixing at theelbows. Another example of such space saving techniques is the use oflong cylindrical tanks for the brine solution which can be mounted alongthe sides of the truck bed.

[0090] In another more detailed aspect of the present invention, eachunit can be configured as a modular unit such that upon review of theparticular contaminated water stream a set of units can be delivered toa site for quick assembly by coupling the individual units. Modularunits are substantially complete units that generally merely need to beconnected to one another and/or a power source for operation. Forexample, individual units might include an initial filtration unit,electrocoagulation unit, advanced oxidation unit, solids filter unit,ion-exchange unit, and ozone production-destruction unit. One or more ofeach unit can be supplied depending on the desired capacity and thenature of the contaminated water.

[0091] It is to be understood that the above-referenced arrangements areonly illustrative of the application for the principles of the presentinvention. Numerous modifications and alternative arrangements can bedevised without departing from the spirit and scope of the presentinvention. While the present invention has been shown in the drawingsand fully described above with particularity and detail in connectionwith what is presently deemed to be the most practical and preferredembodiment(s) of the invention, it will be apparent to those of ordinaryskill in the art that numerous modifications can be made withoutdeparting from the principles and concepts of the invention as set forthherein.

What is claimed is:
 1. A system for remediation of contaminated watercomprising: a) an initial filtration unit having filters for removing atleast particulates above about 100 μm from an influent water stream toproduce a filtered contaminated water; b) an electrocoagulation unitoperatively connected to the initial filtration unit for receiving thefiltered water and capable of causing precipitation, flocculation,and/or destruction of at least a portion of contaminants within thefiltered wastewater; c) an oxidation treatment unit operativelyconnected to the electrocoagulation unit wherein a remediativelyeffective amount of oxidizing agent is introduced into the water; and d)a polishing unit for removing additional minor amounts of contaminants.2. The system of claim 1, wherein the amount of oxidizing agent isbetween about 4 ppm and 200 ppm.
 3. The system of claim 1, wherein theoxidizing agent is ozone.
 4. The system of claim 1, further comprisingan ion-exchange unit including at least one set of columns packed withan ion-exchange medium.
 5. The system of claim 4, wherein theion-exchange medium is a zeolite.
 6. The system of claim 4, furthercomprising an ammonium destruction unit operatively connected to the atleast one set of columns, wherein the ammonium destruction unitincludes: a) a fresh brine source operatively connected to the at leastone set of columns for delivering a brine solution to the columns havingsufficient replacement ions to remove substantially all ammonium in theion-exchange medium to produce an ammonium-containing brine; b) aconcentrated ammonium tank operatively connected to the at least one setof columns for receiving the ammonium-containing brine solution; c) areactor also operatively connected to the at least one set of columnsfor receiving the ammonium-containing brine solution; and d) a flowcontrol member connected to the at least one set of columns andconfigured for directing flow of the ammonium-containing brine solutionto either the concentrated ammonium tank or the reactor based on theconcentration of ammonium in the ammonium-containing brine solution. 7.The system of claim 1, wherein the initial filtration unit comprises atleast one screen filter and a gravimetric classifier.
 8. The system ofclaim 1, wherein the polishing unit is a microfiltration unit forremoving particulates greater than about 1 μm in size.
 9. The system ofclaim 1, wherein each unit is modular.
 10. A system for ammonium removaland destruction comprising: a) an ion-exchange unit including at leastone set of columns packed with an ion-exchange medium; b) a fresh brinesource operatively connected to the at least one set of columns fordelivering a brine solution to the columns having sufficient replacementions to remove substantially all ammonium in the ion-exchange medium toproduce an ammonium-containing brine; c) a concentrated ammonium tankoperatively connected to the at least one set of columns for receivingthe ammonium-containing brine solution; d) a reactor also operativelyconnected to the at least one set of columns for receiving theammonium-containing brine solution; and e) a flow control memberconnected to the at least one set of columns and configured fordirecting flow of the ammonium-containing brine solution to either theconcentrated ammonium tank or the reactor based on the concentration ofammonium in the ammonium-containing brine solution.
 11. The system ofclaim 10, wherein the ion-exchange medium is a zeolite.
 12. The systemof claim 10, wherein the reactor includes at least one static mixerpipe, said static mixer pipe comprising: a) an outer substantiallycylindrical housing having a length and an inner substantiallycylindrical member concentrically positioned within the outer housingsuch that an annular space is formed between the outer housing and innermember; and b) a flow directioning member spirally placed in the annularspace spanning at least a portion of the length of the outer housing.13. The system of claim 11, further comprising a degas unit operativelyconnected to the reactor, said degas unit comprising: a) a generallycylindrical outer housing having a central vertical axis, a fluid inlet,a fluid outlet, and a gas release outlet; b) an inner cylindrical pipealong a length of the outer housing and concentrically placed andconnected at a top end to the gas release outlet, said inner pipe havinga plurality of slits; and c) a flow directioning member spirally placedin a space between the outer housing and the inner pipe and configuredto direct fluid flow downward in a spiral path toward the fluid outlet.14. A method for remediation of contaminated water comprising the stepsof: a) filtering the contaminated water to remove at least particulateslarger than about 100 μm; b) electrocoagulating the contaminated water;and c) treating the contaminated water with a remediatively effectiveamount of an oxidizing agent.
 15. The method of claim 14, furthercomprising the step of removing additional contaminants using anion-exchange medium selected from the group consisting of zeolites,ceramics, chabazite, carbon, and mixtures thereof.
 16. The method ofclaim 14, further comprising the steps of: a) removing collectedcontaminants from the ion-exchange medium using a brine solution toproduce a contaminant-rich brine solution; and b) exposing the brinesolution to an effective amount of bromine and ozone sufficient toconvert the ammonium to other nitrogen-containing species.
 17. Themethod of claim 16, wherein the step of exposing further comprisesdiverting an initial volume of contaminant-rich brine solution to aconcentrated ammonium tank followed by redirecting the contaminant-richbrine solution to a reactor wherein the step of exposing is performedsuch that a small volume of contaminant-rich brine solution is added tothe reactor from the concentrated ammonium tank.
 18. The method of claim14, further comprising the step of pretreating the contaminated waterusing ozone prior to the step of electrocoagulating the contaminatedwater.
 19. The method of claim 14, further comprising the step ofmicrofiltrating the contaminated water subsequent to the step oftreating the contaminated water using filters sufficient to removeparticulates having a size greater than about 1 μm in size.
 20. Themethod of claim 15, further comprising the step of disinfectingsubsequent to the step of removing additional contaminants using ozone.